Support expanded builder to confom to Sendable when original object explicitily conforms to Sendable

Author: alschmut

Sources/BuildableClient/main.swift

@@ -45,8 +45,8 @@ enum MyEnum {
 }
 
 @Buildable
-class MyClass {
-    var m1: String = ""
+final class MyClass: Sendable {
+    let m1: String
 
     init(
         m1: String

Sources/BuildableMacro/Enum/GenerateBuilderFromEnum.swift

@@ -13,8 +13,11 @@ func generateBuilderFromEnum(enumDecl: EnumDeclSyntax) throws -> StructDeclSynta
         type: TypeSyntax(stringLiteral: enumDecl.name.text),
         value: try getFirstEnumCaseName(from: enumDecl)
     )
-    
-    return StructDeclSyntax(name: getStructBuilderName(from: enumDecl.name)) {
+
+    return StructDeclSyntax(
+        name: getStructBuilderName(from: enumDecl.name),
+        inheritanceClause: getSendableInheritanceClause(original: enumDecl.inheritanceClause)
+    ) {
         MemberBlockItemListSyntax {
             MemberBlockItemSyntax(decl: makeVariableDeclWithValue(enumMember: enumMember))
             MemberBlockItemSyntax(

Sources/BuildableMacro/StructAndClass/GenerateBuilderFromClass.swift

@@ -11,7 +11,9 @@ func generateBuilderFromClass(classDecl: ClassDeclSyntax) throws -> StructDeclSy
     guard let initialiserDecl = getFirstInitialiser(from: classDecl.memberBlock) else {
         throw "Missing initialiser"
     }
-    let structMembers = extractInitializerMembers(from: initialiserDecl)
-
-    return makeStructBuilder(withStructName: classDecl.name, and: structMembers)
+    return makeStructBuilder(
+        structName: classDecl.name,
+        inheritanceClause: classDecl.inheritanceClause,
+        structMembers: extractInitializerMembers(from: initialiserDecl)
+    )
 }

Sources/BuildableMacro/StructAndClass/GenerateBuilderFromStruct.swift

@@ -8,8 +8,11 @@
 import SwiftSyntax
 
 func generateBuilderFromStruct(structDecl: StructDeclSyntax) -> StructDeclSyntax {
-    let structMembers = getStructMembers(structDecl: structDecl)
-    return makeStructBuilder(withStructName: structDecl.name, and: structMembers)
+    makeStructBuilder(
+        structName: structDecl.name,
+        inheritanceClause: structDecl.inheritanceClause,
+        structMembers: getStructMembers(structDecl: structDecl)
+    )
 }
 
 private func getStructMembers(structDecl: StructDeclSyntax) -> [StructMember] {

Sources/BuildableMacro/StructAndClass/Helper/MakeStructBuilder.swift

@@ -7,8 +7,15 @@
 
 import SwiftSyntax
 
-func makeStructBuilder(withStructName structName: TokenSyntax, and structMembers: [StructMember]) -> StructDeclSyntax {
-    StructDeclSyntax(name: getStructBuilderName(from: structName)) {
+func makeStructBuilder(
+    structName: TokenSyntax,
+    inheritanceClause: InheritanceClauseSyntax?,
+    structMembers: [StructMember]
+) -> StructDeclSyntax {
+    StructDeclSyntax(
+        name: getStructBuilderName(from: structName),
+        inheritanceClause: getSendableInheritanceClause(original: inheritanceClause)
+    ) {
         MemberBlockItemListSyntax {
             for structMember in structMembers {
                 MemberBlockItemSyntax(decl: makeVariableDecl(structMember: structMember))

Sources/BuildableMacro/Utils/GetSendableInheritanceClause.swift

@@ -0,0 +1,26 @@
+//
+//  File.swift
+//  Buildable
+//
+//  Created by Alexander Schmutz on 14.05.25.
+//
+
+import SwiftSyntax
+
+func getSendableInheritanceClause(
+    original originalInheritanceClause: InheritanceClauseSyntax?
+) -> InheritanceClauseSyntax? {
+    guard let inheritedSendableType = originalInheritanceClause?.inheritedTypes.first(where: { $0.isSendableIdentifier }) else {
+        return nil
+    }
+    return InheritanceClauseSyntax(
+        colon: TokenSyntax.colonToken(leadingTrivia: .spaces(0), trailingTrivia: .space),
+        inheritedTypes: InheritedTypeListSyntax([inheritedSendableType])
+    )
+}
+
+private extension InheritedTypeSyntax {
+    var isSendableIdentifier: Bool {
+        type.as(IdentifierTypeSyntax.self)?.name.text == "Sendable"
+    }
+}

Tests/BuildableMacroTests/BuildableClassTests.swift

@@ -180,5 +180,46 @@ class BuildableClassTests: XCTestCase {
             macros: testMacros
         )
     }
+
+    func test_should_make_class_sendable() {
+        assertMacroExpansion(
+            """
+            @Buildable
+            class MyClass: Sendable {
+                let m1: String
+
+                init(
+                    m1: String = ""
+                ) {
+                    self.m1 = m1
+                }
+            }
+            """,
+            expandedSource: """
+
+            class MyClass: Sendable {
+                let m1: String
+
+                init(
+                    m1: String = ""
+                ) {
+                    self.m1 = m1
+                }
+            }
+
+            struct MyClassBuilder : Sendable {
+                var m1: String = ""
+
+                func build() -> MyClass {
+                    return MyClass(
+                        m1: m1
+                    )
+                }
+            }
+
+            """,
+            macros: testMacros
+        )
+    }
 }
 

Tests/BuildableMacroTests/BuildableEnumTests.swift

@@ -147,5 +147,32 @@ class BuildableEnumTests: XCTestCase {
             macros: testMacros
         )
     }
+
+    func test_should_make_enum_sendable() {
+        assertMacroExpansion(
+            """
+            @Buildable
+            enum MyEnum: Sendable {
+                case myCase
+            }
+            """,
+            expandedSource: """
+
+            enum MyEnum: Sendable {
+                case myCase
+            }
+
+            struct MyEnumBuilder : Sendable {
+                var value: MyEnum = .myCase
+
+                func build() -> MyEnum {
+                    return value
+                }
+            }
+
+            """,
+            macros: testMacros
+        )
+    }
 }
 

Tests/BuildableMacroTests/BuildableStructTests.swift

@@ -433,6 +433,36 @@ class BuildableStructTests: XCTestCase {
         )
     }
 
+    func test_should_make_struct_sendable() {
+        assertMacroExpansion(
+            """
+            @Buildable
+            struct MyObject: Sendable {
+                let m1: () -> String
+            }
+            """,
+            expandedSource: """
+
+            struct MyObject: Sendable {
+                let m1: () -> String
+            }
+
+            struct MyObjectBuilder : Sendable {
+                var m1: () -> String = {
+                    return ""
+                }
+
+                func build() -> MyObject {
+                    return MyObject(
+                        m1: m1
+                    )
+                }
+            }
+            """,
+            macros: testMacros
+        )
+    }
+
     func test_should_set_default_value_for_defined_types() {
         assertMacroExpansion(
             """